1. Field of the Invention
The present invention relates to a multi-function peripheral device capable of performing a variety of functions, such as a facsimile function and a modem function.
2. Description of Related Art
In recent years, multi-function peripheral devices capable of performing a variety of different functions, such as a facsimile function, a copy function, and a modem function, have become popular.
When a multi-function peripheral device is connected in serial with a remote device, the multi-function peripheral device can receive transmission data transmitted in succession one bit at a time from the remote device, it is conceivable that the multi-function peripheral device be designed to transfer the received transmission data to an external device such as a personal computer.
Data can be transferred to the external device using packet transmission. That is, each time the multi-function peripheral device receives a predetermined amount of transmission data, the multi-function peripheral device transfers the received transmission data to the external device as packet data. The multi-function peripheral device can transfer transmission data to the external device more efficiently in packets than when transferring the transmission data serially one bit at a time.
In the packet transmission, packet data, including a header portion and a data portion, is transmitted as a single group of data. The header portion indicates the length of data in the packet, and the data portion includes the actual data of interest. When the external device receives the packet data, the external device recognizes the data portion and the end of the packet data based on the data length indicated in the header portion. The external device retrieves the data from the data portion and performs processings such as storing the data in a memory of the external device itself.
In this conceivable packet data transfer operation, however, the transfer amount, that is, the amount of data in a single packet, is fixed. Therefore, when a reception speed, at which the multi-function peripheral device receives transmission date from the remote device, is relatively high, the transmission data will quickly accumulate to an amount sufficient to make a packet. In this case, the interval between successive packet transfers becomes relatively short. On the other hand, when the reception speed is relatively slow, relatively a long period of time will be required to accumulate transmission data sufficient to form a transfer packet. As a result, the interval between transfers of packets will become relatively long. When the period of time between transfers of packets is too long, then the external device will generate an error (time-out error) because excessive time has elapsed since the last packet has been received. Such an error can result in termination of transfer operations. Transfer processes can not be precisely performed.
It is therefore an objective of the present invention to overcome the above-described problems and provide an improved multi-function peripheral device that is capable of changing a transfer amount of transmission data, to be transferred to an external device in each packet, in accordance with the reception speed of the transmission data.
In order to attain the above and other objects, the present invention provides a multi-function peripheral device, comprising: means capable of receiving transmission data serially transmitted from a remote device; means for identifying a reception speed, at which the reception means receives the transmission data, means for changing, based on the identified reception speed, an amount of the transmission data to be transferred to an external device as a data unite and means for transferring, to the external device, the received transmission data by successive data units, each data unit being comprised of the changed amount of the transmission data.
Accordingly, the amount of transmission data, to be transferred at a time in a data unit to the external device, can be changed dependently on the reception speed. In the case where the reception speed is slow, the amount of transmission data, to be transferred as a data unit to the external device, can be made smaller than the amount of transmission data, to be transferred as a data unit to the external device when the reception speed in high. It is therefore possible to prevent the time interval, at which successive data units of the transmission data are transferred to the external device, from increasing even when the reception speed is low. It is possible to prevent the external device from generating a time-out error even in the case where the reception speed is slow.
The transferring means may transfer the transmission data in parallel to the external device. Accordingly, the transform speed con be made large in comparison with the reception speed.
The changing means may include, transfer timer storing means for storing data of a period of time, during which the serially-received transmission data is accumulated into each of the successive data units s and means for changing the amount of the transmission data, to be accumulated into each data unit, dependently on the identified reception speed and the period of time stored in the transfer time storing means.
With this structure, it is possible to change the period of time, during which the transmission data is to be accumulated into each data unit. Accordingly, the amount of transmission data, to be transferred in each data unit, can be changed to a desired value. For example, the period of time, during which the transmission data is to be accumulated into each data unit, can be made as long as possible within a range wherein the external device will generate no time-out errors. In this case, it is possible to set an large an possible the amount of transmission data to be transferred in each data unit. Accordingly, transmission data can be transferred to the external device with high efficiency.
The multi-function peripheral device may further comprises first transmission means for transmitting day data to the external device; time measuring means for measuring time elapsing after the first transmission transmits dummy data to the external device; error signal reception mans for receiving a time-out error signal from the external device time out period storing means for, when the error signal reception means receives the time out error signal, storing data of a time measured by the time measuring means to have elapsed until a time-out error signal is received; and first control means for controlling the transfer timer storing means to store data of the period of time, during which transmission data is to be accumulated into each data unit, based on data of the time stored in the time out period storing means.
With this structure, dummy data is experimentally transmitted to the external device so that the external device will generate a time-out error. Based on time elapsed until a signal indicative of the time-out error is received, the time period, during which transmission data should be accumulated into each data unit, can be automatically set as appropriate for the external device.
Or, the multi-function peripheral device may further comprises second transmission means for repeatedly transmitting dummy data to the external device at a time interval; first transmission time interval storage means for storing data of the time interval, at which the second transmission means transmits dummy data; first error signal reception means capable of receiving a time-out error signal from the external device: and second control means for, when the time-out error signal is received, controlling the transfer timer storing means to store the time period, during which transmission data is to be accumulated into each data unit, based on the time interval stored in the first transmission time interval storage means.
Accordingly, when a time out error signal is received when dummy data is repeatedly transmitted to the external device experimentally at a certain time interval S, the period of time, during which transmission data should be accumulated into each data unit, can be automatically set as appropriate for the external device based on the time interval S.
In this case, the multi-function peripheral device may further comprise third control means for, when no time-out error signal in received, increasing the time interval to stored in the first transmission time interval storage means and controlling the second transmission means to transmit dummy data to the external device at the increased time interval presently stored in the first transmission time interval storage means. Accordingly, when no time-out error is generated, the time interval, at which dummy data is transmitted, is increased and transmission of dummy data is repeated until a time-out error is generated. It is therefore possible to detect an optimum transmission interval, and accordingly to set an optimum value to the period of time, during which transmission data should be accumulated into each data unit.
Or, the multi-function peripheral device may further comprises third transmission means for repeatedly transmitting dummy data to the external device at a time interval; second transmission time interval storage means for storing data of the time interval, at which the third transmission means transmits dummy data; second error signal reception means capable of receiving a time-out error signal from the external device; and fourth control means for, when no time-out error signal is received, controlling the transfer timer storing means to store the time period, during which transmission data is to be accumulated into each data unit, based on the time interval stored in the second transmission time interval storage means.
Accordingly, then no time out error signal is received in response to the dummy data repeatedly transmitted to the external device experimentally at a certain time interval Sxe2x80x2, the time period, during which transmission data should be accumulated into each data unit, can be automatically set as appropriate to the external device based on the time interval Sxe2x80x2.
In this case, the multi-function peripheral device may further comprise fifth control means for, when a time-out error signal is received, decreasing the time interval stored in the second transmission time interval storage means and controlling the third transmission mans to transmit dummy data to the external device at the decreased time interval presently stored in the second transmission time interval. Accordingly, when a time-out error is generated, the time interval, at which dummy data is transmitted, is decreased and transmission of dummy data is repeated until no time-out error is generated. It is therefore possible to detect an optimum transmission interval, and to set an optimum value to the period of time, during which transmission data is to be accumulated into each data unit.
According to another aspect, the present invention provides a multi-function peripheral device, comprising: a reception portion capable of receiving transmission data serially transmitted from a remote device; a speed identifying unit identifying a reception speed, at which the reception portion receives the transmission data; a changing unit changing, based on the identified reception speed, an amount of the transmission data to be transferred to an external device as a data unit; and a transferring unit transferring, to the external device, the received transmission data by successive data units, each data unit being comprised of the changed amount of the transmission data.